Fuel burner assembly



United States Patent Ofiice 3,033,273 Patented May 8, 1962 3,033,273FUEL BURNER ASSEMBLY John S. Zink, Jr., Robert P. Duncan, Orville 1.Edwards, and Robert D. Reed, Tulsa, Okla, assignors to John ZinkCompany, Tulsa, Okla, a corporation of Delaware Filed Nov. 9, 1959, Set.No. 851,779 2 Ciaims. (Cl. 158-7) The present invention relates to fuelburners and more specifically pertains to such equipment for industrialpurposes for burning gaseous fuel and atomized liquid fuel. Thisinvention pertains to improvements over the multiple fuel burnerdisclosed and claimed in Zink et al. Patent 2,851,093.

An object of the invention is to provide a continuous annular ledge onthe burner assembly adjacent the burner tips for the gaseous fuel and toprovide for a discharge of gaseous fuel along the downstream face of theledge and into a low pressure zone downstream of the ledge so as tomaintain stable kindling of the gaseous fuel about the entirecircumference of the ledge and maintaining stable burning of the gaseousfuel throughout extreme ranges of fuel flow and providing a burnerassembly wherein the shape of the flame may be adjusted.

Other objects and features of the invention will be appreciated andbecome apparent to those skilled in the combustion art as the presentdisclosure proceed and upon consideration of the following detaileddescription taken with the accompanying drawing wherein one generalorganization of the burner is disclosed along with a modification of theburner tips for the gaseous fuel.

In the drawing:

FIG. 1 is an axial sectional view of a burner assembly exhibiting theinvention and taken on the line 11 of FIG. 2

FIG. 2 is a plan view on a smaller scale with an illustration of a pilotfor the gaseous fuel burner tips omitted.

FIG. 3 is an enlarged fragmentary section of a portion of the shroudtaken on the line 33 of FIG. 1 with one of the gaseous fuel burner tipsshown in plan.

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 3.

FIG. 5 is a fragmentary sectional view taken on the .line 5-5 of FIG. 3.

FIG. 6 is a view similar to FIG. 3 illustrating a modification of aburner tip for the gaseous fuel.

FIG. 7 is a fragmentary sectional view taken on the line 7-7 of FIG. 6.

A fuel burner assembly exhibiting the invention is adapted forindustrial purposes and is designed to be mounted on a wall 10 such asthe floor of a structure or furnace to be fired. This wall is providedwith a cylindrical shaped opening 11 for accommodating a generallycylindrical shaped ceramic or refractory shroud member or tile 12. Thisshroud or tile may be supported within the opening 11 by any suitablemeans and resilient or yieldable heat resistant material 16 may beprovided within the opening 11 around the periphery of the tile 12 withthe material 16 serving to accommodate expansion and contraction of theshroud and the wall 10. An annular flange is carried by the upstream endof the shroud 12 and this flange may be formed integral with the ceramicmember which make up the annular tile 12. The flange 15 provides acontinuous ledge having a downstream face 17 which lies in a planesubstantially at right angles to the axis of the burner assembly and theaxis of the shroud 12.

The burner assembly includes means for supporting gaseous fuel burnertips and a burner for atomized liquid fuel for firing into the space tobe heated and such means includes an annular member 18 which is adaptedfor attachment to the wall 10. A disc-shaped member 21 is maintained inspaced relation from the annular member 18 by a plurality ofcircumferentially spaced bolts 22. An air register stator 19 and an airregister rotor 23 are provided between the disc-shaped member 21 and theannular member 18. The air register rotor or sleeve 23 may be rotated bymeans of one or more handles 24. The air register stator or sleeve 19 isprovided with apertures 26 and the air register rotor or sleeve 23 isprovided with apertures 27 which are adapted to register with theapertures 26 to control volume of secondary air admitted for movementthrough the large central opening '30 in the shroud 12.

A member 28 formed of refractory material is mounted on the disc-shapedmember 21 and it has a cylindrical exterior surface. The refractory 28has a frusto-conical shaped inner surface 29 which flares outwardly inproceeding downstream from a liquid fuel burner nozzle 3-1. The liquidfuel burner nozzle may be mounted on the disc-shaped member 21 in anysuitable manner and supplied with primary air so as to provide foratomization of the liquid fuel issuing from the nozzle 31. A pilot 32may be provided for the liquid fuel burner as shown. The disc-shapedmember 21 carries an annular manifold 33 into which a gaseous fuelmixture is supplied under pressure through a conduit fitting 34. Aplurality of pipes 36 are connected to and are in open communicationwith the manifold 33 and extend downstream therefrom. The pipes 36 maybe equally spaced circumferentially of the burner assembly and eachcarries a burner tip 37 for gaseous fuel.

The structure of each burner tip 37 and its relationship with the shroud12 and particularly the ledge face 17 will be best appreciated uponconsideration of FIGS. 3, 4 and 5. Each burner tip 37 is connected tothe upper end of its supply pipe 36 and this portion of the tipstructure may have flat sides for threading the tips onto the respectivepipes 36. One of the flat faces is adapted to lie along the innercircumference 38 of the annular flange 15. The downstream end portion ofeach nozzle 37 is frusto-conical shaped. One discharge port 41 isprovided in each nozzle 37 as shown in FIGS. 3 and 5. The axis of thedischarge port 41 is at an acute angle with respect discharge port 41 ineach gaseous fuel burner tip 37 provides for the discharge of a portionof the gaseous fuel generally radially outward as will be apparent froma consideration of FIG. 3 and towards the inner surface of the shroud 12downstream of the ledge 17 as Will be apparent from a consideration ofFIG. 5. The axis of each port 41 in relation to the axis 40 of theassociated tip is at an acute angle and the angle indicated Z in FIG. 5is desirably at forty-five degrees.

Each burner tip 37 for the gaseous fuel is provided with two additionaldischarge ports 43 and 44. The axis of the discharge port 43 is inalignment with the radius 42 as shown in FIG. 3, The axis of thedischarge port 43 and the axis of the discharge port 44 are desirably atan acute angle with respect to the axis 40 of the associated burner tip37 and the angle indicated at W in FIG. 4 is desirably at forty-fivedegrees for the discharge port 43 and for the discharge port 44. Theports 43 and 44 provide for the discharge of gaseous fuel in directionswhich are generally radially inward towards the axis 50 of the burnerassembly. The axis of the discharge ports 43 and 44 diverge from eachother in proceeding inwardly. In the embodiment illustrated in thedrawing the angle M indicated in FIG. 3 is at about thirty-six degrees.The gaseous fuel discharged through the ports 43 and 44 provides for aflame having one length. If a longer flame is desired the angle betweenthe axes of the ports 43 and 3 44 is decreased, If a short flame isdesired the angle M is increased. If a still shorter flame is desiredthe axis of the port 43 is caused to deviate from the radial positionshown in FIG. 3 and converge at a smaller angle M with respect to theaxis of the discharge port 44,

A modified burner tip for the gaseous fuel is shown at 37A in FIGS. 6and 7. This burner tip is cylindrical shaped in the portion where itjoins the associated supply pipe 36. The burner tip 37A is mountedclosely adjacent the inner surface 38 of the flange 15. This burner tipis provided with a discharge port 41 (FIG. 6) which is adapted todischarge the gaseous fuel over the downstream face 17 of the ledge andit is arranged at an angle X with respect to the radius 42 in a manneras hereinabove described. The discharge ports 43 and 44 of the nozzle37A are arranged in the same manner as that described in connection withthese discharge ports in the nozzle 37.

A frusto-conical shaped shield 46 is provided which surrounds a majorportion of each nozzle 37A. A portion of the shield 46 is omitted in thevicinity of the downstream face 17 of the ledge as will be appreciatedupon consideration of FIGS. 6 and 7. The downstream surface 47 of theshield 46 constitutes a projection of the ledge face 17. Thus the lowpressure condition which exists adjacent the downstream face 17 of theledge exists adjacent the downstream face 47 of each shield 46, Thegaseous fuel which escapes through the discharge port 41 of any one ofthe burner tips 37 or 37A and upon kindling by a pilot (not shown)causes the flame to run along the downstream face 17 of the continuousledge to provide for kindling of all of the burner tips 37 or 37A.Extremely stable kindling is maintained for the reason that thesecondary air in moving through the annular area 30 creates a lowpressure zone at the downstream face 17 of the ledge. This low pressurezone or an annular low pressure area results from the secondary airmoving at substantial velocity and there is a pressure drop across theburner assembly. The low pressure is proportional to the square of thepressure drop and the greater the velocity of the secondary air the moreextensive and the lower the pressure will be to thereby hold the gaseousfuel at the downstream face 17 of the ledge for extremely good kindlingand stable burning of the gaseous fuel.

The gaseous fuel issuing from all of the discharge ports from eachburner tip 37 or 37A provides for extremely stable combustion and thiscondition exists for maximum flow of the gaseous fuel or at a minimumflow. The burner operates well when turned down from a one hundredpercent of designed gas flow to two percent of the designed gas flowwith complete stability in a burner devoid of monitored automaticcontrol and when the burner assembly is supplied with typical fuel gasand without reference to the required kindling temperature of the gaswhich is being used. This stability exists regardless of the air flowacross the burner.

While the invention has been described with reference to specificstructural features and with regard to a multiple fuel burner it will beappreciated that changes may be made in the various elements of thecombination and changes may be made in the overall assembly. Suchmodifications and others may be made without departing from the spiritand scope of the invention as set forth in the appended claims.

What we claim and desire to secure by Letters Patent is:

1. In a fuel burner assembly, a shroud having a substantiallycylindrical inner surface, a continuous annular flange projectinginwardly from the inner surface of said shroud presenting a ledge havinga continuous annular downstream face, a plurality of circumferentiallyspaced burner tips each having a side portion lying along andsubstantially in contact with the inner circumference of said flangewith tip portions thereof extending beyond the downstream face of saidledge, means for supplying gaseous fuel under pressure to said burnertips, means guiding air for movement downstream of the assembly andaxially over the inner circumference of said flange, means forcontrolling the volume of said air, each of said burner tips having adischarge port therein positioned downstream of said flange, and eachdischarge port directing gaseous fuel towards said inner surfacedownstream of said ledge and having its axis disposed at an acute anglewith respect to a radial plane of the burner assembly which intersectsthe longitudinal axis of the associated burner tip.

2. In a fuel burner assembly, a shroud having a substantiallycylindrical inner surface, a continuous annular flange projectinginwardly from the inner surface of said shroud presenting a ledge havinga continuous annular downstream face, a plurality of circumferentiallyspaced burner tips mounted closely adjacent and substantially inengagement with the inner circumference of said flange with tip portionsthereof extending beyond the downstream face of said ledge, means forsupplying gaseous fuel under pressure to said burner tips, means guidingair for movement downstream of the assembly and axially over the innercircumference of said flange, means for controlling the volume of saidair, each of said burner tips having a discharge port therein positioneddownstream of said flange, each discharge port directing gaseous fueltowards said inner surface downstream of said ledge and having its axisdisposed at an acute angle with respect to a radial plane of the burnerassembly which intersects the longitudinal axis of the associated burnertip, a shield carried by each burner tip in the vicinity of said ledgeand upstream of said port, and each shield extending throughout theportion of the associated burner tip inwardly of the inner circumferenceof said flange.

References Cited in the file of this patent UNITED STATES PATENTS1,885,478 Powers Nov. 1, 1932 2,826,249 Poole Mar. 11, 1958 2,840,152Reed June 24, 1958 2,851,093 Zink et al. Sept. 9, 1958 2,918,966Ferguson Dec. 29, 1959

